Improvement in combustion chamber for combustion engines



Jufy 19, 1932. E. A. SPERRY ,682:

IMPROVEMENT IN COMBUSTION CHAMBER FOR COMBUSTION ENGINES Filed Aug. 5. 1922 2 Sheets-Sheet .1 Q

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IMPROVEMENT E. A. SPERRY 7 1,867,682

IN COMBUSTION CHAMBER FOR COMBUSTION ENGINES FiledAuE- 1922 7 2 Sheets-Sheet 2 L.D.C. ADC

ghvmioz I fl/vm/ij mfix Patented July 19, 1932 UNITED STATES PATENT OFFICE ELMER A. SPERRY, OF BROOKLYN, NEW YORK, ASSIGNOR TO SPERRY DEVELOPMENT COMPANY, OF DOVER GREEN, DELAWARE, A CORPORATION OF DELAWARE IMPROVEMENT IN COMBUSTION CHAMBER FOR COMBUSTION ENGINES Application filed August 5, 1922. Serial 1T0. 579,863.

My invention relates to combustion engines and has for its object the provision of an improved device of this character.

More specifically, my invention relates to r a novel method of increasing the efficiency of two-cycle combustion engines by supercharging. I accomplish the supercharging of such an engine by providing suitable ports in the cylinders, and sources of high and low pressure fluids, the communication between said sources and said ports being controlled by a sliding valve, which is arranged to permit the low pressure fluid to scavenge the combustion chamber after an explosion, and to supercharge the combustion chamber with hi h pressure fluid on the ascending stroke of t e piston.

Another novel feature of my invention is the provision of a plurality of air pumps,

each having high and low pressure chambers, arranged oppositely with respect to each other, and interconnected with the cylinders, so that a novel form of sliding valve may cause the desired pressure to be supplied and connect the idle chamber of the pumps to air.

Another novel feature of my invention is the provision of means for obtaining the highest efllciency in turbulence in the combustion chamber by creating a vortical condition by gradually building up the velocities to very high values, as contra-distinguished from a sudden gush or jet followed by a slowing down of the velocity which defeats the object of my invention by creating eddies.

Other novel features of my invention reside in the arrangement and construction of parts to accomplish its object.

My invention will be better understood from the following description taken in connection with the accompanying drawings, and its scope will be pointed-out in the appended claims.

In the drawings, illustrating what I now consider to be a preferred form of my invention,

Fig. 1 is a front elevation of a two cylinder combustion engine, with parts shown in section.

Fig. 2 is an enlarged detail of the piston and combustion chamber, viewed at right angles to the position shown in Fig. 1, with a modified construction of the part forming the cylinder head.

Fig. 3 shows curves indicating the piston velocity and displacement, respectively.

Referring to the drawings, in Fig. 1, there are shown two cylinders 1, 2, having piston rods 3, 4, respectively, operatively connected to the respective crank pins 5, 6, on a crank shaft 7 The construction of the two cylinders being preferably identical, it will not be necessary to describe but one, for which purpose cylinder 1 has been shown insection.

A piston 8 is suitably secured tothe rod 3, and arranged to reciprocate within the cylinder 1 in the usual manner. The piston chamber of the cylinder indicated at 9, is connected by a cylindrical passage or throat 10, having a peculiar contour, to be fully described hereinafter, to a combustion chamber 11, in which are located a fuel injection valve or atomizer 12 and an ignition plug 13, (if

desired). passage 14, formed in the cylin-,

der frame surrounds the space 9 as shown, for water circulation. In operation, the combustion chamber 11 becomes hot enough to ignite the charge. As shown in Fig. 1, the combustion chamber 11 is of the hot bulb type and is eccentrically positioned with respect to the vertical axis of the piston chamber 9. The purpose of this arrangement will later appear.

parallel series of ports 15, 16, which I prefer to extend around the cylinder. The lower series of ports 16, is located so as tozfully communicate with the chamber 9, just as the piston 8 reaches the end of its expansion or descending stroke. These ports 16, are closed by the piston on its com ression. or ascending stroke, shortly after sai' stroke begins. The

ports '16 communicate with a closed chamber The cylinder is formedpreferably with two square inch, which source will be fully described hereinafter. The face of the piston 8 is in the form of a truncated cone, as-indicated at 20 (Fig. 2), whose vertex is eccentrically located with respect to the center line of the piston chamber, so as to present a longer and more gradual slope ad acent ports 16 nearest the passage 19. A cylindrical member or plug 20' is seated on the truncated face of the cone ortion 20, best illustrated in Fig. 2. Preferably, this plug is made of nichrome steel, better to withstand the pressure and high tem erature from the combustion chamber. Thls plug is suitably secured to the member 20, and is arranged to cooperate with the throat 10 to create the desired turbulent condition in the combustion chamber, as will From the foregoing, it will be seen that when the piston 8 is at the end of its descending stroke, low pressure air may enter the ports 16, sweeping over the cone portion 20, by which the air is directed upwardly. Since the air pressure varies inversely with the distance, the air entering the ports 16 nearest the supply 1passage 19 is directed upwardly by the gradua ly sloping face of member 20, while the air entering the more remote ports 16 is directed upwardly by the steeper slope of member 20, so as to obtain a more eflicient scavenging of the piston chamber 9, to which further reference will be made. The passage 10 to the combustion chamber 11, which is also shown as being eccentric with respect to the vertical axis of the piston chamber 9, is arranged to receive the cone member 20. Obviously, by this arrangement, the incoming air currents are directed by the piston face upwardly in columns eccentric to the vertical axis of the piston chamber to the passage 10.

To attain the highest efficiency in turbulence in the combustion chamber 11, especially with gas of the high density employed in engines of this character, the prime consideration is a gradual but rapid acceleration of the gases confined to proportions that can be practically carried out, with a'minimum consumption of power in creating such turbulence. To accomplish this, I have devised a contour or configuration of the throat 10, which is such as to utilizethe gradually decreasing piston velocities together with the decreasing piston displacement as the top dead center is approached, which will give a gradual acceleration to the air jet itself up to high velocities, terminating not necessarily at the top, but somewhere near this point, with the .highest velocity in the cycle. The purpose of this is to gradually though positively energize the vortex and raise it to very high values through prolonged tangential impingement of the jet.

The vortex is the ideal condition of turbulence causing intimate comingling of the oil all parts of the combustion chamber space. The importance of' securing a high velocity vortex action may be realized when it is remembered that in the Diesel engine only a very small fraction of a second is allowed to inject the oil, mix it with the air, and ignite it, since all of this takes place at a certain oint in. the stroke inside of the cylinder. ne of the principal purposes of this invention is to make up for the extreme shortness of the time by extremely high swirling velocities of the air. I have found that proper air velocities cannot be produced by a sudden gush or jet of air into the combustion space but that the inertia factor of the air must be reckoned with and a. large velocity gradually built up without creating wasteful eddies. be later described.

The plug 20 is preferably of a substantially conical formation, with its greatest diameter at its base, as plug 20 tapers from its base upwardly to a certain point 20" intermediate between the top and the base. Beyond point 20' the block may or may not flare slightly for a distance to point 20 from where the plug again tapers upwardly to its top. At its base the plug is enlarged so as to coincide with and form a continuation of the sloped surface of the cone portion 20 of the piston. As will later appear, the throat 10 is most constricted at one point. Since the plug is of greatest diameter at a single point, obvi ously, it will require less energyfor the plug to force air through the most constricted portion by this arrangement, than it would, if the plug were of a uniform diameter, since if the plug were of a uniform diameter, there would e less clearance between it and the other parts of the throat 10, and of course, greater opposition to the passage of air.

In order to give a gradual yet rapid acceleration to the air entering the combustion chamber 11, the throat 10 is formed with a peculiar contour or with varying diameters, the smallest of which is preferably located near its upper end, in the vicinity of the point indicated at 10', but at a point adjacent or below the effective diameter 20 of the plug 20' when it is at the end of its compression stroke. From its most constricted portion 10' downwardly to a point near its lower opening, say at 10", the diameters within the throat vary, and gradually-increase in size, but not necessarily in equal steps. For instance, as shown in Fig. 2, the upper part of the contour of the throatbetween the points 10 and 10" is steeper than the lower part. The diameters of the throat 10 are determined by the piston velocity, the ratio of the smallest diameter of the throat to the entire area of the cylinder, the compression ratio, and the ratio of the largest part of the plug to the most constricted portion of the throat. The contour of the throat 10, will of course vary with any of its determining factors. It may be varied to obtain any desired air velocity through its most constricted portion and must be designed in view of the variable factors mentioned present in a given case, the general law, well known to those skilled in the art, of the velocity of gases under compression through orifices, controlling. The lower portion of the throat 10 from the point 10" downwardly, flares outwardly substantially to coincide with the cone surface of the plug 20 and member 20, and of course is also determined by the variable factors mentioned to create the desired air acceleration.

In Fig. 3, the curve A is a representative curve of piston displacement from top dead center for any crank angle from 0 to 180 degrees, the exact contour of the curve depending on the scales used, length of piston stroke and the ratio of the length of the connecting rod to the length of the crank. The case takenis for a 6 inch stroke with a ratio of 4.5. In the figure, the ordinates indicate the crank angles, 0, indicating the top dead center of the piston. The abscissaeindicate the length of the piston stroke. It will be observed that when the crank has turned through 180 degrees, the piston has completed its full stroke of 6 inches, and is at lower dead center (L. D. 6.). This curve illustrates the abruptlydecreasing piston displacement as the top dead center (T. D. C.) is approached.

In Fig. 3 there is also shown a representative curve B of piston velocity for any crank angle from 0 to 180 degrees, the exact contour depending on the factors mentioned above, the point of maximum velocity being also controlled by these factors. In the case taken, the piston reaches a maximum .velocity of about 24 feet per second at 80 degrees when working at a given rate (R. P. M.) This curve illustrates the gradually decreasing piston velocity as the top dead center is approached.

The crank angle at which the plug enters the throat is dependent on the length of the stroke, length of the throat, the angle of the cylinder head and the height of the plug. As the plug 20 approaches throat 10, the piston velocity decreases gradually while piston displacement decreases abruptly. As the piston continues its compression stroke,

the plug enters the throat, moving successively past the points 10" and 10', gradually accelerating the velocity of the air past the point 10. The most constricted portion of the throat at 10' being below the top dead centerof the cap 20 permits the air jet to be forced upwardly and kept in motion after the widest portion of the cap 20" has passed the mostconstricted part of the throat. The accelerated column of air through the most constricted part of the throat is directed to the upper wall of the combustion chamber 11,

' which is formed to radially direct the jet downwardly over the side wall of the chamher to create a vortex in a well understood manner. While this feature of my invention is preferably with a plug eccentrically mounted on the piston face, it may be advantageously employed when the plug is otherwise located. It is of course understood that that the term gradual as used in the claims is intended to include a constant acceleration.

. The collector chamber 17 (Fig. 1) is provided with a series of ports 21, in communication with a chamber 22 formed Within the cylinder casing concentric with the piston chamber, and said chamber 22 has a series of ports 23 leading to the open air. The chamber 22 is provided with a series of ports 24, leading to a collector chamber 25, which cominunicates with an exhaust passage 26. Said chamber 22 is also provided with a series of ports 27, leading to a. collector chamber 28, which communicates with a source of high pressure air,say 20 pounds per square inch.

The upper series of ports 15 also communicate with the chamber 22, and are opened and closed by the descending and ascending stroke of the piston, respectively, on the side within the cylinder. The outer or opposite end of the ports 15 is controlled by a sliding valve 29, which may connect them with either ports 24 or 27. The valve 29 is of cylindrical formation, concentrically positioned with respect to piston chamber 9, and located within the chamber 22. Said valve is formed with three parallel series of circumferential ports 30, 31, 32 and is arranged to reciprocate oppositely to the piston of its cylinder with the proper lead and lag factors.

As shown in Fig. 1, the piston rods 3, 4, are separated 180, which of course causes the pistons of cylinders 1, 2, to reciprocate oppositely. In order to accomplish the opposite reciprocation of the valves 29 in their proper phase, that is approximately in guadrature with their respective pistons 8,

have provided a rocker 33, shown in Fig. 1 withthe front half broken away, formed with two parallel arms 35, journaled at their middle points on bearings 36. The arms 35 are suitably united by parallel cross-pieces 42 to form a rocking unit about the bearings 36. Each of the valves 29 of the respective cylinders 1, 2, are connected to the rocker 33 by rods 43 and 44, respectively. The rods 43 are suitably secured, preferably diametrically opposite to the piston 8 at one end. At their opposite ends, said rods are formed with sockets to receive balls 45, indicated by dash 'fore obvious that when said disk 47 rotates,

the travel of said shoe, carrying the ball 51, will rock the rocker 33, and thereby oppositely reciprocate the valves 29 of the two cylinders in a manner readily understood. However, in order that the respective valves 29 will reciprocate in proper phase with the respective pistons of their cylinders, the eccentric slot 48 has been so positioned as to bring this about. 7

As previously indicated herein, two difi'erent air pressures are employed in my invention, namely a high pressure of say about 20 pounds per square inch and a low pressure of say about 3 pounds per square inch. The high pressure air is employed to supercharge the engines, and the low pressure is employed to scavenge the combustion chambers. This air may be provided in any suitable manner, but I preferably provide two air pumps for the cylinders 1, 2 respectively. The air pumps may each comprise a cylinder 54, in which a piston is arranged to reciprocate, said piston being actuated by a rod 56. The cylinder 54 has high pressure and low pressure chambers, which arrangement is well known in the art. The high pressure chamber communicates with cylinder 1 through a passage 59 to the collector chamber 28 and ports 27. The low pressure chamber is connected by a passage 60 to the passage of cylinder 2 corresponding to passage 19. The other air pump is in every respect similar to the first pump, except that its high and low pressure chambers are reversed.

The reason therefor is obvious, when it is recalled that the cylinder 2 which it supplies, operates in a direction opposite to the cylinder 1. c

Having described one embodiment of the structural details of my invention, its operation will be readily understood.

Assuming that the piston 8 has just reached the end of its ascending stroke, and that the combustion chamber 11 is filled with air under heavy pressure, the turbulence in the combustion chamber having taken place through the vortical operation hereinbefore described in detail. At this moment the member 20 is within the cylindrical passage 10, the atomizer.12 has injected the fuel and the charge is ignited either automatically or by the plug 13. Now, since the member 20' is not exactly fitted into the cylindrical passage 10, the explosive gases pass into the chamber 9. The piston 8 is impelled downwardly, and as it continues its downward movement, the port 15 is opened. In the meantime, the valve 29 has ascended bringing the port 15 through its port 31 into communication with port 24, leading to the exhaust passage 26. The combustion gases can now escape through the passage 24. Continuing its downward movement, the piston 8 uncovers port 16, which admits low pressure air. This air is caused to sweep into the chamber 9 by the peculiar formation of the piston face in the mannerdescribed, and thoroughly scavenge the chamber 9. The piston 8 having reached the end of its descending stroke commences to ascend, the valve 29 simultaneously descending. The piston being near its dead center is moving comparatively slowly, while valve 29 is moving relatively faster. As the piston 8 ascends, the port 16 is being closed by it, the port 15 being first closed by the valve 29, at which time the chamber 9 is now full of low pressure air. Then as. the piston 8 continues to slowly ascend, the valve quickly descends bringing port 15 into communication with port 27, connected to the high pressure air-source, through the valve port 30, thereby supercharging the chamber-9. Continuing its upward movement, the iston closes port 15, thereby shutting off the high pressure air, and the valve 29 continues to descend, thereby placing port 27 in communication with chamber 22, andbringing ports 21, 32, into communication, thereby opening a passage between chambers 17, 22. In the meantime, the piston 8 completes its ascending stroke, whereupon the charge is ignited in themanner described, and the cycle of operations repeated.

While I have described my invention as embodied in concrete form in accordance with the provisions of the patent statutes, it should be understood that I do not limit my invention thereto, since various modifications thereof will suggest themselves to those skilled in the art without departing from the spirit of my invention, the scope of which is set forth in the annexed claims."

Having herein described my invention,

what I claim and desire to secure by Letters the vertical axes of said hot bulb and apex being in alignment, said axes being positioned nearer the ports furthestjemoved from said source.

2. In a combustion engine, the combination with the cylinder, iston, intake ports adapted to be uncovered by the piston, and a source of fluid supply at one side connected to said ports, of a combustion space eccentric to the vertical axis of the piston, a convex top on said piston formed to direct inflowin air upwardly an eccentrically located plug t ere on, said convex top having its vertex coincident with the axis of said plug and a throat connecting said cylinder with said combustion space arranged to cooperate with said top and plug having cooperating contours whereby the air passing through it is graduw ally accelerated, said plug being positioned nearer the ports furthest removed from said source. v i 3. In a combustion engine, the combination with the cylinder and combustion chamber of a throat connecting said cylinder and chamber, a piston having a convex top, a tapering plug mountedon said piston with its widest part near the top thereof arranged to reciprocate within said throat, the most constricted portion within said throat being located slightly below the widest part of said plug when it is at the extreme end of its compression stroke.

4. In a combustion engine, the combina- .tion with'the cylinder and combustion chamber of a throat having continuously varyin diameters throughout its length as describe and a piston carrying a plug arranged'to reciprocate within said throat, which plug is formed with its largest diameter near its up-' per end, and gradually decreases in size as its base is approached. v I

5. In a combustion engine, the combination with the cylinder and combustion chamber 40 of a throat having continuously varying di- 1 ameters throughout its length as described, and a piston carrying a plug arranged to reciprocate within said throat, which plug is formed with its largest diameter near its .45 face, which is located above the most constricted portion of said throat, when the piston is at the end of its compression stroke, said plug tapering to a smaller diameter near its base. I 6. In a two-cycle combustion engine, the

combinationwith the cylinder, piston and circumferential intake ports adapted to be uncovered by the piston, of a source of pres sure air for charging said cylinder connect- 5 ed .to said ports,-said piston having a convex or dome shaped top with the apex thereof'to that side of the center of the piston furthest from the connection of the said ports to said source of pressure air.

In testimony whereof Ihave alfixed my' signature. J

p ,ELMIER A. SPERRY, 

